EONYX is a terminal AI agent for working with code, written in Go. It connects directly to any OpenAI-compatible API (OpenAI, OpenRouter, DeepSeek, Moonshot, local Ollama / llama.cpp / LM Studio) — no external services, no telemetry, no OAuth. One process, one binary, everything local. Here: installation, the first run, and the full configuration.

EONYX and Claude Code are both terminal AI agents for working with code, and their workflow is similar: MCP, skills, hooks, subagents, plan mode, sessions. The difference is in the architecture and the freedom. Claude Code is tied to the cloud and to Anthropic models; EONYX is not. Here is what that gives you in practice.

Besides the interactive TUI, EONYX can run headless — perform a task and exit. That is what you need for scripts, pipes and CI: predictable output, JSON events and meaningful exit codes.